“The reason this investigation started was because of an allegation of him supplying methamphetamine in exchange for sex,” Hardin said.

Fairfax County police began investigating Silverthorne late last month when they received a tip from a citizen who said the mayor was distributing meth through a website used to arrange sex between men, Hardin said.

An undercover detective created a fake profile on the site and was contacted by Silverthorne within two days, Hardin said. After exchanging texts, the detective agreed to meet with Silverthorne for group sex if he provided drugs, Hardin said.

On Thursday, undercover members of the police department’s Organized Crime and Narcotics Division met Silverthorne at a local hotel, received two grams of methamphetamine from the mayor and later arrested him, Hardin said.

Two men suspected of supplying Silverthorne with drugs were also arrested. Juan Jose Fernandez, 34, and Caustin Lee McLaughlin, 21, both of Maryland, face charges including felony distribution of methamphetamine.

Silverthorne did not solicit money in exchange for the drugs, Hardin said.

An attorney for Silverthorne was not immediately available for comment.

Silverthorne was elected this year to serve his third term as mayor of Fairfax, a middle-class city with a population of about 22,500. He is also a substitute teacher for the Fairfax County Public Schools.

Councilman Jeffrey Greenfield will serve as acting mayor in Silverthorne’s absence, the city said in a statement.